1. Field
The present application relates to gas turbines, and more particularly to an arrangement and method to minimize flow induced vibration in a gas turbine exhaust diffuser.
2. Description of the Related Art
The turbine exhaust cylinder and the turbine exhaust manifold are coaxial gas turbine casing components connected together establishing a fluid flow path for the gas turbine exhaust diffuser. The fluid flow path includes an inner flow path and an outer flow path defined by an inner diameter delimiting an outer cylindrical surface of the inner flow path and an outer diameter delimiting an inner cylindrical surface of the outer flow path, respectively. Tangential struts are arranged within the fluid flow path and serve several purposes such as supporting the flow path and provide a pathway for lubrication piping. Turbine exhaust cylinder and turbine exhaust manifold tangential struts are arranged in circumferential rows and extend between the outer cylindrical surface and the inner cylindrical surface. For the last row of turbine exhaust cylinder tangential struts in the direction of flow, every other turbine exhaust cylinder tangential strut may be aligned, axially, with a turbine exhaust manifold strut. As an example, there may be six turbine exhaust cylinder tangential struts arranged in a circumferential row and three turbine exhaust manifold tangential struts aligned axially with every other turbine exhaust cylinder strut.
At certain conditions, unsteadiness of the exhaust flow around the tangential struts can cause vibrations of the inner and outer diameter of the turbine exhaust cylinder and the turbine exhaust manifold. The strut flow unsteadiness may cause large oscillations in flow path pressures that force the flowpath structure to vibrate or even resonate strongly. These vibrations are a potential contributor to damage occurring on the flow path of the turbine exhaust manifold and the turbine exhaust cylinder. This damage to the diffuser flow path may require replacement or repair.